Purification and Structural Analysis of The Nucleocapsid of PRRS Virus Expressed from Escherichia coli
猪繁殖与呼吸综合征病毒N蛋白的原核表达、纯化与结构分析

The DNA fragment encoding the nucleocapsid protein (N) of PRRSV BJ4 strain were cloned into the BamH I / EcoR I sites of pET28a vector to construct the expression plasmid pET28-N by designing special primers. The soluble protein (P28-N) were obtained by introducing the expression plasmid into E. coli BL21 (DE3) host cell, and the amount of recombinant protein reached to 28% of the total mass of bacterial protein. PET28-N were purified by nickel-affinity column of Proband resin. The circular dichroism (CD) analysis showed that the purified PET28-N shared a significant (26%) alpha-helical structure, beta-sheet (23.7%), beta-turn (19.8%), and random coil (30.3%), respectively. Finally,the secondary structure of N protein of PRRSV was deduced.